<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="/网页展示/js/jquery-3.4.1.min.js"></script>
    <style>
        .d{
            height: 100px;
            width: 100px;
            background:red;
            position: relative;
            top: 350px;
        }
        .d2{
            height: 10000px;
        }
    </style>
</head>
<body>
    <div class="d"></div>
    <button>开始</button>
    <div class="d2"></div>
    <script>
        $(function(){
            $(document).scroll(function(){
                console.log( $(document).scrollTop())
                if($(document).scrollTop() >550){
                $('.d').animate({top:'700px'},1000)
            }
        })
        })
    </script>
</body>
</html>